<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>TypeScript</title>
</head>

<body>
    <script src="demo.js"></script>
</body>

</html>
<!-- tsc --init: 配置-->
<!-- tsc --watch: 监视（实时转换） -->